Glass sheets or plates are used in the construction of a wide variety of items including doors, windows, furniture, mirrors, and insulating glass units. Typically, a glass sheet or plate is mounted using an adhesive and/or a sealant. For an adhesive and/or a sealant to properly adhere to a glass sheet or plate, the glass sheet or plate must be clean. As a result, glass sheet washing machines have been developed.
Known glass sheet washing machines include a top row of rotating brush rollers spaced apart from a bottom row of rotating brush rollers. Sprayers spray a washing or rinsing liquid on each rotating brush roller. A conveyor includes drive rollers positioned adjacent to the rotating brush rollers of each row, which move the glass sheets through the washing machine at a controlled speed. The glass sheets are passed through the conveyor with one large face up and one large face down. The top row of rotating brush rollers acts on one large face of the glass and the bottom row acts on the other large face.
Recently, the market for glass windows and doors has been driven by the use of low emissivity (“low-e”) and other energy efficient coated glass. Many of these coatings can be scratched or otherwise damaged by the glass washing machines of the prior art that use a single brush speed. Some prior art washing machines attempted to address this problem by the use of a two-speed brush having a low and a high-speed setting. Other prior art glass washing machines raise the brushes to reduce contact with the glass or use special brushes in an effort to eliminate the scratching problem. However, these methods may either reduce the effectiveness of the washing machine or require repositioning or changes of the brushes.
There is a need for a glass washing machine wherein the linear speed of the glass sheet along a path of travel through the glass washing machine and the rotational speed of the brushes are dependant upon one another such that a change in one automatically results in a corresponding change in the other.